Thrips resistant cabbage

ABSTRACT

The invention relates to a  Brassica  plant in particular a  Brassica oleracea  plant comprising a genetic determinant, which when homozygously present confers high resistance against  Thrips tabaci,  and which is as found in plants grown from seeds of which a representative sample is deposited with the NCIMB under NCIMB accession number 41760. Preferably, the plant is homozygous for the genetic determinant and resistant against  Thrips tabaci.  The genetic determinant in the seeds of NCIMB deposit 41760 is located on chromosome 2 and linked to marker BO00200 (SEQ ID NO: 1) and/or marker BO00277 (SEQ ID NO: 2) and/or BO00602 (SEQ ID NO: 5).

RELATED APPLICATIONS AND INCORPORATION BY REFERENCE

This application is a continuation of U.S. application Ser. No.13/799,104 filed Mar. 13, 2013, now pending U.S. Pat. No. 9,765,357,which claims benefit of European Patent Application Serial No.12164775.4 filed Apr. 19, 2012.

The foregoing applications, and all documents cited therein or duringtheir prosecution (“appln cited documents”) and all documents cited orreferenced in the appln cited documents, and all documents cited orreferenced herein (“herein cited documents”), and all documents cited orreferenced in herein cited documents, together with any manufacturer'sinstructions, descriptions, product specifications, and product sheetsfor any products mentioned herein or in any document incorporated byreference herein, are hereby incorporated herein by reference, and maybe employed in the practice of the invention. More specifically, allreferenced documents are incorporated by reference to the same extent asif each individual document was specifically and individually indicatedto be incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to Brassica plants, in particular Brassicaoleracea plants resistant to Thrips tabaci, to seeds and progeny fromthe seeds and plants, and to a method for producing such a plant.

BACKGROUND OF THE INVENTION

The present invention relates to Brassica plants, in particular Brassicaoleracea plants which are resistant to Thrips tabaci and herein displayagronomically desirable traits.

Thrips tabaci (also known as Onion thrips, or simply thrips) is a highlypolyphagous insect and considered as an economically harmful pest formany cultivated crops especially for crops from the Liliaceae,Solanaceae, and Brassicaceae plant families, such as onion, leek,tomato, cabbage, but also in crops from outside these families, such ase.g. cucumber, melon and snap beans (Toda & Murai, 2007, AppliedEntomology and Zoology 42: 309-316; Trdan et al., 2005, AfricanEntomology 13: 85-95).

Thrips harm the plant directly by feeding on the plant tissue andindirectly by being a vector for lethal plant viruses such as tomatospotted wild virus (Toda & Murai, 2007, Applied Entomology and Zoology42: 309-316). Thrips occur worldwide and due to climate change and tradethe frequency of thrips infestation is increasing (Trdan et al., 2005;African Entomology 13: 85-95).

Cabbage plants (Brassica oleracea var. capitata L.) belong to the plantfamily Brassicaceae. The family has a cosmopolitan distribution andconsists of approximately 3500 to 4000 species. The family andespecially the genus Brassica contains many agronomically importantcrops such as broccoli, Brussels sprouts, cauliflower, Chinese cabbage,curly cabbage, kale, kohlrabi, mustard, oxheart cabbage, radish,rapeseed, red cabbage, Savoy cabbage, turnip, and white cabbage.

In tissue of Brassica oleracea var. capitata plants affected by thripscallus growths will form. Over time these callus growths become brownmaking it necessary to remove several layers of leaves from the cabbagehead before marketing. Even in storage the development of symptomscaused by thrips may increase. The reduction in head size and weightultimately leads to a loss in yield. For Brassica oleracea var. capitatait is estimated that 75% of its total acreage suffers from thrips.

Controlling thrips in cabbage by means of applying insecticide isconsidered environmentally unfriendly and ineffective, because theclosed leaves of the cabbage heads provide protection to the thrips, andbecause thrips are hard to detect, sometimes even only at harvest stage.Thrips infestation in cabbages may occur from the second exterior leafup to the fifteenth exterior leaf, while insecticides are usually onlyeffective up to the sixth exterior leaf of the head (Trdan et al., 2005;African Entomology 13: 85-95). Therefore, there is an urgent need forcabbage plants which are resistant against this pest.

Although no highly thrips resistant Brassica oleraceae varieties areknown, huge differences in susceptibility exist among varieties. Certainvarieties show an intermediate level of resistance, but no varieties areknown that are highly resistant against Thrips tabaci. The geneticbackground of this intermediate resistance against thrips is stillpoorly understood and it is thought that this is a polygenic trait,inherited as a gene complex in which many genes are involved (Voorripset al., 2008; Euphytica 163: 409-415).

Citation or identification of any document in this application is not anadmission that such document is available as prior art to the presentinvention.

SUMMARY OF THE INVENTION

Because in the present state of the art no highly thrips resistantcabbage varieties are known, it is the object of the present inventionto provide a Brassica plants, in particular Brassica oleracea plant witha high resistance to Thrips tabaci.

In the research that led to the present invention novel Brassicaoleracea plants were developed that are highly resistant against thrips.

The said resistance of the invention is controlled by a geneticdeterminant, the inheritance of which is consistent with that of amonogenic additive trait. ‘Additive trait’ in this case means that thefully achievable resistance is only observable in plants which maycomprise the genetic determinant in homozygous state, however plantswhich may comprise the genetic determinant in heterozygous state willshow an intermediate level of resistance.

Since the inheritance of the resistance is comparable to that of amonogenic trait, it has a second advantage over the prior art, becausethe resistance level is not only higher but also easier to incorporatein new Brassica varieties as compared to the complex polygenic traitsfrom the prior art which led to plants with only an intermediateresistance against thrips.

Accordingly, it is an object of the invention to not encompass withinthe invention any previously known product, process of making theproduct, or method of using the product such that Applicants reserve theright and hereby disclose a disclaimer of any previously known product,process, or method. It is further noted that the invention does notintend to encompass within the scope of the invention any product,process, or making of the product or method of using the product, whichdoes not meet the written description and enablement requirements of theUSPTO (35 U.S.C. §112, first paragraph) or the EPO (Article 83 of theEPC), such that Applicants reserve the right and hereby disclose adisclaimer of any previously described product, process of making theproduct, or method of using the product.

It is noted that in this disclosure and particularly in the claimsand/or paragraphs, terms such as “comprises”, “comprised”, “comprising”and the like can have the meaning attributed to it in U.S. Patent law;e.g., they can mean “includes”, “included”, “including”, and the like;and that terms such as “consisting essentially of” and “consistsessentially of” have the meaning ascribed to them in U.S. Patent law,e.g., they allow for elements not explicitly recited, but excludeelements that are found in the prior art or that affect a basic or novelcharacteristic of the invention.

These and other embodiments are disclosed or are obvious from andencompassed by, the following Detailed Description.

DEPOSITS

Seeds of Brassica oleracea plants resistant to Thrips tabaci weredeposited under NCIMB deposit accession number 41760 on 29 Sep. 2010with NCIMB Ltd. (Ferguson Building, Craibstone Estate, Bucksburn,Aberdeen, AB21 9YA). All seeds of the deposit comprise the geneticdeterminant homozygously. Plants grown from these seeds are thus highlyresistant against Thrips tabaci.

The Deposits with NCIMB Ltd, Ferguson Building, Craibstone Estate,Bucksburn, Aberdeen AB21 9YA, UK, under deposit accession number 41760were made pursuant to the terms of the Budapest Treaty. Upon issuance ofa patent, all restrictions upon the deposit will be removed, and thedeposit is intended to meet the requirements of 37 CFR §§1.801-1.809.The deposit will be irrevocably and without restriction or conditionreleased to the public upon the issuance of a patent and for theenforceable life of the patent. The deposit will be maintained in thedepository for a period of 30 years, or 5 years after the last request,or for the effective life of the patent, whichever is longer, and willbe replaced if necessary during that period.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description, given by way of example, but notintended to limit the invention solely to the specific embodimentsdescribed, may best be understood in conjunction with the accompanyingdrawings.

FIG. 1. Schematic overview of a part of chromosome two indicatingmarkers (in bold) that may be linked to the genetic determinantconferring thrips resistance (SEQ ID NO 1, 2, 3, and 5) together withflanking markers (SEQ ID NO: 4, 6, and 7). On the left side the geneticdistance indicated in centiMorgans. On the right side, the markers areindicated.

DETAILED DESCRIPTION OF THE INVENTION

The present invention thus relates to a Brassica plant, in particular aBrassica oleracea plant, which may comprise a genetic determinant, whichwhen homozygously present confers high resistance against Thrips tabaci,and which is as found in plants grown from seeds of which arepresentative sample is deposited with the NCIMB under NCIMB accessionnumber 41760.

The present invention also relates to a Brassica plant, in particular aBrassica oleracea plant, which may comprise the genetic determinantheterozygously, and thus showing intermediate resistance against Thripstabaci, and which genetic determinant is obtainable from plants grownfrom seeds of which a representative sample is deposited with the NCIMBunder NCIMB accession number 41760.

The invention furthermore relates to a Brassica plant which may comprisethe genetic determinant homozygously, and therefore is highly resistantagainst Thrips tabaci.

In one embodiment the invention provides a Brassica plant, in particulara Brassica oleracea plant, that is resistant to Thrips tabaci,obtainable by crossing a resistant plant of which representative seedwas deposited under NCIMB number 41760 with another cabbage plant toproduce an F1 and subsequently selfing the F1 to obtain an F2 andselecting a plant therefrom that shows resistance to Thrips tabaci.

Furthermore, it was found during the research leading to the presentinvention that the genetic determinant conferring resistance to Thripstabaci, is located on chromosome 2 and linked to marker BO00200 (SEQ IDNO: 1) and/or marker BO00277 (SEQ ID NO: 2) and/or BO00602 (SEQ ID NO:5).

More in particular, in the deposit NCIMB 41760 the genetic determinantconferring resistance to Thrips tabaci, is located on chromosome 2between marker BO00458 (SEQ ID NO: 7) and marker BO01225 (SEQ ID NO: 6)and linked to marker BO00200 (SEQ ID NO: 1) and/or marker BO00277 (SEQID NO: 2) and/or marker BO00602 (SEQ ID NO: 5).

Most in particular the genetic determinant conferring resistance toThrips tabaci, is located on chromosome 2 between marker BO01146 (SEQ IDNO: 3) and marker BO00310 (SEQ ID NO: 4) and linked to marker BO00200(SEQ ID NO: 1) and/or marker BO00277 (SEQ ID NO: 2) in seeds depositedunder NCIMB accession number 41760, see also FIG. 1.

Alternatively the genetic determinant conferring resistance to Thripstabaci, is located on chromosome 2 between markers BO00310 (SEQ ID NO:4) and BO00458 (SEQ ID NO: 7) and linked to BO00200 (SEQ ID NO: 1)and/or marker BO00277 (SEQ ID NO: 2) and/or marker BO01146 (SEQ ID NO:3) and/or marker BO00602 (SEQ ID NO: 5), in particular between markerBO00458 (SEQ ID NO: 7) and marker BO01146 (SEQ ID NO: 3) and linked tomarker BO00602 (SEQ ID NO: 5).

Therefore, the invention also relates to a Brassica plant resistant toThrips tabaci, which may comprise a genetic determinant that confersresistance to Thrips tabaci, wherein said genetic determinant isobtainable by introgression from a plant grown from seeds of which arepresentative sample was deposited with the NCIMB under NCIMB accessionnumber 41760, and wherein the said genetic determinant in the seeds ofthe seed deposit number NCIMB 41760 is positioned on chromosome 2 andlinked to marker BO00200 (SEQ ID NO: 1), and/or BO00277 (SEQ ID NO: 2),and/or marker BO00602 (SEQ ID NO: 5).

A Brassica plant carrying the genetic determinant conferring resistanceagainst thrips may suitably be identified among descendants from a crossbetween a plant susceptible for thrips, and a plant that does carry thegenetic determinant in homozygous state, by growing F2 plants from seedsthat are the result from the initial cross and a selfing step, andselecting plants showing the desired trait. Selecting the plants may bedone phenotypically, or may be done through identification of thegenetic determinant, for example by means of one or more of the markersdefined herein.

In the absence of molecular markers or in the event that recombinationbetween the molecular markers and the genetic determinant have takenplace and thus are not predictive anymore, equivalence of geneticdeterminants may still be determined by an allelism test. To perform anallelism test, material that is homozygous for the known determinant, atester plant, is crossed with material that is homozygous for thegenetic determinant that is to be tested. This latter plant is referredto as the donor plant. The donor plant to be tested should be or shouldbe made homozygous for the genetic determinant to be tested. The skilledperson knows how to obtain a plant that is homozygous for the geneticdeterminant to be tested. When in the F2 of the cross between a donorplant and a tester plant no segregation for the phenotype related to thegenetic determinant is observed, the genetic determinants of the donorplant and the tester plant have been proven to be equivalent or thesame.

The invention also relates to a Brassica plant that may comprise agenetic determinant conferring resistance to Thrips tabaci, whereinplants of first generation progeny (F1) of a cross of the said plantwith a tester plant, that may comprise the said genetic determinant andof which representative seed was deposited with the NCIMB underaccession number NCIMB 41760, or a progeny plant thereof that maycomprise the said genetic determinant, or a plant derived therefrom andwhich may comprise the said genetic determinant, show a 1:0 segregationfor the resistance against Thrips tabaci. In both the tester plant andthe plant of the invention the genetic determinant is present inhomozygous form. Plants of the second and further generations, ifobtained by selfing also show a 1:0 segregation for the said resistancepattern. The tester plant may be a plant of which representative seedwas deposited with the NCIMB under accession number NCIMB 41760.

The Brassica plant of the invention is preferably a Brassica oleraceaplant, but may also be any other plant of the genus Brassica into whichthe skilled person may introgress the genetic determinant of theinvention, e.g. the following Brassica species: Brassica oleracea,Brassica napus, Brassic campestris, Brassica cretica, Brassica rapa,Brassica juncea, and Brassica nigra. The skilled person knows how tomake interspecific crosses with these species, e.g. by means of embryorescue, protoplast fusion, and other related technologies.

In another embodiment the invention relates to seeds which may comprisethe said genetic determinant conferring resistance against Thripstabaci. A plant grown from the seeds is highly resistant to thrips whenthe genetic determinant is present in homozygous state.

The invention thus further relates to seeds which may comprise saidgenetic determinant and which seeds are capable of growing into plantsthat are highly resistant against Thrips tabaci.

According to a further aspect thereof, the invention relates topropagation material capable of growing into a plant of the invention.

In one embodiment, such propagation material is formed by seed of aBrassica plant of the invention, wherein the plant that may be grownfrom the seed may comprise a genetic determinant of the invention.

In another embodiment the propagation material capable of growing into aplant of the invention is selected from the group consisting ofmicrospores, pollen, ovaries, ovules, embryos, embryo sacs, egg cells,cuttings, roots, root tips, hypocotyls, cotyledons, stems, leaves,flowers, anthers, seeds, meristematic cells, protoplasts, and cells.

In a further embodiment the invention relates to tissue culture ofpropagation material capable of growing into a plant of the invention.

Suitably, the plant produced from the propagation material may comprisethe genetic determinant as found in Brassica plants grown from seeds ofseed lot AG6359-35/39, a representative sample of which was depositedwith the NCIMB under NCIMB accession number 41760. When the geneticdeterminant is present in homozygous state the plant produced shows highresistance to Thrips tabaci, in particular the resistance as observed inBrassica plants grown from seeds of seed lot AG6359-35/39, arepresentative of which was deposited with the NCIMB under NCIMBaccession number 41760. When the genetic determinant is present inheterozygous state the plant shows intermediate resistance.

The invention also relates to progeny of the plants, cells, tissues andseeds of the invention. Such progeny may in itself be plants, cells,tissues or seeds.

As used herein the word “progeny” is intended to mean the first and allfurther descendants from a cross with a plant of the invention that maycomprise the said genetic determinant. “Progeny” also encompasses plantsthat carry the trait of the invention and are obtained from other plantsor progeny of plants of the invention by vegetative propagation ormultiplication.

Therefore, in one embodiment the invention relates to progeny of aBrassica plant which may comprise the genetic determinant of theinvention.

In a further embodiment the invention relates to progeny of Brassicaplants of the invention that are resistant against Thrips tabaci. Theseprogeny plants thus may comprise the genetic determinant conferringresistance against thrips.

In one aspect the invention relates to the harvested part of a Brassicaplant which may comprisie the genetic determinant conferring thripsresistance.

The invention furthermore relates to a food product which may compriseone or more harvested parts of a Brassica plant which may comprise thegenetic determinant conferring thrips resistance.

The harvested part or food product may be or may comprise a cabbagehead, a curd, a stem, a leaf, a root, a sprout, a seed, or any otherpart of a Brassica plant. The harvested part may also be used for theproduction of bio-fuel. The food product or harvested part, may haveundergone one or more processing steps. Such a processing step mightcomprise but is not limited to any one of the following treatments orcombinations thereof: cutting, washing, cooking, steaming, baking,frying, pasteurizing, freezing, grinding, extracting oil, pickling, orfermenting. The processed form that is obtained is also part of thisinvention.

Another aspect of this invention relates to a nucleic acid moleculewhich is causative of resistance against Thrips tabaci. The said DNAmolecule may comprise a DNA sequence which is positioned on chromosome 2between markers BO00458 (SEQ ID NO: 7) and BO01225 (SEQ ID NO: 6), morein particular between markers BO00458 (SEQ ID NO: 7) and BO00146 (SEQ IDNO: 3) , or between markers BO00146 (SEQ ID NO: 3) and BO00310 (SEQ IDNO: 4), or a part thereof.

Yet another aspect of the invention relates to use of the markers andsaid nucleic acid molecule to identify plants which are resistantagainst Thrips tabaci, and/or carry the genetic determinant conferringresistance to Thrips tabaci.

Therefore, in one embodiment the invention relates to the use of markerBO00200 (SEQ ID NO: 1), or marker BO00277 (SEQ ID NO: 2), or markerBO00602 (SEQ ID NO: 5), or the said DNA molecule which may comprise aDNA sequence which is positioned on chromosome 2 between markers BO00458(SEQ ID NO: 7) and BO01225 Q ID NO: 6), or BO00146 (SEQ ID NO: 3) andBO00310 (SEQ ID NO: 4), or BO00458 (SEQ ID NO: 7) and BO00146 (SEQ IDNO: 3), or part thereof, to indentify plants resistant against Thripstabaci, and/or carrying the genetic determinant conferring resistance toThrips tabaci.

The skilled person knows how to develop new markers linked to a traitusing already known markers, QTLs, alleles, genes or other DNA moleculesthat are associated with a certain trait.

Thus, the invention also relates to the use of markers BO00200 (SEQ IDNO: 1), BO00277 (SEQ ID NO: 2), and BO00602 (SEQ ID NO: 5), and the saidDNA molecule, or part thereof, for developing other markers linked tothe genetic determinant conferring thrips resistance.

In one embodiment, the genetic determinant conferring resistance toThrips tabaci also confers resistance against other sap sucking insectspecies, wherein the sap sucking insect species is selected from, butnot limited to the group consisting of Aleyrodes proletella, Myzuspersicae, and Brevicoryne brassicae.

In one aspect the invention relates to a process for producing Brassicaplants which may comprise a genetic determinant that confers resistanceto Thrips tabaci, which may comprise the step of selecting said Brassicaplants from a population of Brassica plants segregating for the saidgenetic determinant using marker BO00200 (SEQ ID NO: 1) and/or markerBO00277 (SEQ ID NO: 2) and/or BO00602 (SEQ ID NO: 5).

The term ‘genetic determinant’ as used herein encompasses one or moreQTLs, genes, or alleles. These terms are used interchangeably. A geneticdeterminant may be identified by the use of a molecular marker. Agenetic determinant may alternatively be identified by the position on agenetic map, or by indication of the location on a linkage group orchromosome. When a genetic determinant is not linked to a specificmolecular marker any longer, but its position on a chromosome as definedon a genetic map is unaltered, this genetic determinant is still thesame as when it was linked to the molecular marker. The genetic traitthat it confers is therefore also still the same. The ‘genetic trait’ isthe trait or characteristic that is conferred by the geneticdeterminant. The genetic trait may be identified phenotypically, forexample by performing a bio-assay. However, also plant stages for whichno phenotypic assay may be performed do carry the genetic informationthat leads to the genetic trait. ‘Trait’ or ‘phenotypic trait’ may beused instead of ‘genetic trait’.

In one embodiment, the invention relates to Brassica plants of theinvention that carry the genetic determinant conferring resistance toThrips tabaci, and having acquired said determinant by introduction ofthe genetic information that is responsible for the trait from asuitable source, either by conventional breeding, or geneticmodification, in particular by cisgenesis or transgenesis. Cisgenesis isgenetic modification of plants with a natural gene, coding for an(agricultural) trait, from the crop plant itself or from a sexuallycompatible donor plant. Transgenesis is genetic modification of a plantwith a gene from a noncrossable species or a synthetic gene.

The invention also relates to the germplasm of plants of the invention.The germplasm is constituted by all inherited characteristics of anorganism and according to the invention encompasses at least the geneticdeterminant of the invention. The germplasm may be used in a breedingprogram for the development of trips resistant Brassica plants.

In one aspect the invention relates to a method for production of aBrassica plant is resistant against Thrips tabaci, which may comprise:

-   -   a) crossing a plant which may comprise a genetic determinant        that leads to resistance against Thrips tabaci with another        plant;    -   b) selfing the resulting F1 for obtaining F2 plants;    -   c) selecting plants resistant to Thrips tabaci in the F2;    -   d) optionally performing one or more additional rounds of        selfing or crossing, and subsequently selecting, for a plant        which may comprise said resistance against Thrips tabaci.

It is clear that the parent that provides the trait of the invention isnot necessarily a plant grown directly from the deposited seeds. Theparent may also be a progeny plant from the seed or a progeny plant fromseeds that are identified to have the trait of the invention by othermeans.

In one aspect, the invention relates to a method for production of aBrassica plant resistant against Thrips tabaci, which may comprise:

-   -   a) crossing a plant which may comprise the genetic determinant        that leads to resistance against Thrips tabaci with another        plant;    -   b) optionally backcrossing the resulting F1 with the preferred        parent;    -   c) selecting for plants resistant to Thrips tabaci in the F2;    -   d) optionally performing one or more additional rounds of        selfing or crossing, and subsequently selecting, for a plant        which may comprise the said resistance is performed.

The invention additionally provides a method of introducing a desiredtrait into a Brassica plant resistant against Thrips tabaci, which maycomprise:

-   -   a) crossing a Brassica plant resistant to Thrips tabaci,        representative seed of which were deposited with the NCIMB under        deposit number NCIMB 41760, with a second Brassica plant that        may may comprise a desired trait to produce F1 progeny;    -   b) selecting an F1 progeny that may comprise said resistance and        the desired trait;    -   c) crossing the selected F1 progeny with either parent, to        produce backcross progeny;    -   d) selecting backcross progeny which may comprise the desired        trait and resistance against Thrips tabaci; and    -   e) optionally repeating steps c) and d) one or more times in        succession to produce selected fourth or higher backcross        progeny that may comprise the desired trait and resistance        against Thrips tabaci. The invention includes a Brassica plant        produced by this method.

In one embodiment selection for plants resistant against Thrips tabaciis done in the F1 by using marker BO00200 (SEQ ID NO: 1) and/or markerBO00277 (SEQ ID NO: 2) and/or BO00602 (SEQ ID NO: 5). In another aspectselection for the trait of the invention is started in the F2 of a crossor alternatively of a backcross. Selection of plants in the F2 can bedone phenotypically as well as by using the said markers.

In one embodiment selection for plants resistant against Thrips tabaciis started in the F3 or a later generation.

In one embodiment the plant which may comprise the genetic determinantis a plant of an inbred line, a hybrid, a doubled haploid, or of asegregating population.

The invention further provides a method for the production of a Brassicaplant resistant against Thrips tabaci by using a doubled haploidgeneration technique to generate a doubled haploid line which maycomprise the said resistance.

The invention furthermore relates to hybrid seed that may be grown intoa thrips resistant plant and to a method for producing such hybrid seedwhich may comprise crossing a first parent plant with a second parentplant and harvesting the resultant hybrid seed, wherein said firstparent plant and/or said second parent plant is the plant as claimed.

In one embodiment, the invention relates to a method for producing ahybrid Brassica plant that is resistant to thrips, which may comprisecrossing a first parent Brassica plant with a second parent Brassicaplant and harvesting the resultant hybrid seed, of which the firstparent plant and/or the second parent plant is resistant against Thripstabaci, and growing said hybrid seeds into thrips resistant hybridplants.

The invention also relates to a method for the production of a Brassicaplant resistant against Thrips tabaci by using a seed that may comprisea genetic determinant in its genome that leads to resistance againstThrips tabaci for growing the said Brassica plant. The seeds aresuitably seeds of which a representative sample was deposited with theNCIMB under deposit number NCIMB 41760.

The invention also relates to a method for seed production which maycomprise growing Brassica plants from seeds of which a representativesample was deposited with the NCIMB under deposit number NCIMB 41760,allowing the plants to produce seeds, and harvesting those seeds.Production of the seeds is suitably done by crossing or selfing.

In one embodiment, the invention relates to a method for the productionof a Brassica plant resistant against Thrips tabaci by using tissueculture.

The invention furthermore relates to a method for the production of aBrassica plant resistant against Thrips tabaci by using vegetativereproduction.

In one embodiment, the invention relates to a method for the productionof a Brassica plant resistant against Thrips tabaci by using a methodfor genetic modification to introgress the said resistance into theBrassica plant. Genetic modification may comprise transgenicmodification or transgenesis, using a gene from a non-crossable speciesor a synthetic gene, and cisgenic modification or cisgenesis, using anatural gene, coding for an (agricultural) trait, from the crop plantitself or from a sexually compatible donor plant.

The invention also relates to a breeding method for the development ofBrassica plants that are resistant against Thrips tabaci whereingermplasm which may comprise said resistance is used. Representativeseed of said plant which may comprise the genetic determinant and beingrepresentative for the germplasm was deposited with the NCIMB underdeposit number NCIMB 41760.

In a further embodiment the invention relates to a method for theproduction of a Brassica plant resistant against Thrips tabaci whereinprogeny or propagation material of a plant which may comprise thegenetic determinant conferring said resistance is used as a source tointrogress the said resistance into another Brassica plant.Representative seed of said plant which may comprise the geneticdeterminant was deposited with the NCIMB under deposit number NCIMB41760.

The invention provides preferably a Brassica plant resistant to Thripstabaci, which plant is obtainable by any of the methods herein describedand/or familiar to the skilled person.

SEQUENCE DATATable 1: Sequence data of the SNP markers of FIG. 1. In NCIMB deposit41760 the markers BO00200,BO00277, and BO00602 are linked to the geneticdeterminant conferring resistance against Thrips. BO00200TTGTCCGGAAAATAAGCCCTTCCTTCTCCATGAGCCGCCCAA SEQ ID NO: 1ACTCCTAAAGTACTTACC[T/C]TCCATTCCTTTCAGCACTATTGACGGACAGTCCTTGATGGTCACGCTTGTGAACCTGCAG BO00277GCTTGTCCAGCTTATGAGCATTTTGTAATACATGTTTGCTTGG SEQ ID NO: 2ATGGTCAAACCTGAAAA[A/C]ACACACAAGTTCAACAATTCT CAGAAGATGGATAAACCTGCAGBO01146 TTAAAAACAAATNATGTTTTGTTTTACCTGCTTTTTCCTCTTCT SEQ ID NO: 3CGCTNNTTGNCAGCTTCTTCTCTCTGTTGGCGAATCAGAGCCAAACGATCTGTACACAAACACACACAAGGGATAAGATAATCAA[A/*]TAGGCTCATCTGGTAACAAAGAAAGAGAACAAGAGGTCCATTGTTTTTTTACNNAANTCCTTNNTTGNTTGCTCGGTTTTNNCNTGNNNCTGCAACCTCATGTATCGCTCATGAGCTCGTTG CTTCTCTAGCTCCTCCCTGCAGBO00310 CATGTCATCTTTCGTNAGGTTTGTTATTTCTATGCCTCGTTTG SEQ ID NO: 4AGAGCTTCCCTCAATGG[A/C]CCCATAGTTGCATCTTTCACTAGGTTCTTCATGTCTGATCCCGAGTACCCTGCAG BO00602TTAAATATGTGAATGCTGAAATRTTTGTTTAGCAGA[C/G]GAG SEQ ID NO: 5ACACAGGAAGAAGATCATCTCATGTTGTTCGCTCTCTCAGCAGAGAGTTTGAAGTTGCAAGTACTCCTGCAG BO01225CCCTGTTWAAGGAGCCTCCTTGGAGCTTGTTGATACCTCAAA SEQ ID NO: 6GTTAGGTAGTGACAATGTGGATAATGAAAGTTTGAAGCTTT[A/C]TCAACAATTAGCTGATAAGAGAGGTTCTTGTGAAGAGGATTTGATGAGAATCTCTATGAAGAAACGAGGTGTAATCAGCAATGTCTCCACCTCTYTGATGGAARATGCTRGTTTYGATGGAAT ATTGGCTTCTCCTGCAG BO00458TAAAGAACCTGATGAAGAAAGTGAAGAGCTAGGTGGAAACC SEQ ID NO: 6TACTTGACCTGCTCCTAAG[T/G]TTCTTCACTTCCGGGATCTTCTCCTCTTTTGATCTCACCTGCCTCACCTTTGCCTCGTTC

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of the invention as defined in the appended claims.

The present invention will be further illustrated in the followingExamples which are given for illustration purposes only and are notintended to limit the invention in any way.

EXAMPLES Example 1

Thrips resistant plants of the invention were compared with susceptibleplants and plants with an intermediate resistance in an open fieldtrial. Plants were naturally infected by using an attractant species. Inthis trial leek plants were used as a natural attractant for thrips. Forthe skilled person it is known that also other plants can be used as anattractant for Thrips tabaci, such as onion or shallots.

Plants from variety Rinda and Hurricane were used in this trial assusceptible control plants. Plants from varieties Langendijker Bewaar,Tacoma, and Multima were included in this trial since they are known tobe intermediately resistant against Thrips tabaci. As highly resistantplants of the invention, plants grown from seeds of seed lotAG6359-35/39 of which a representative sample was deposited with theNCIMB under NCIMB accession number 41760, as well as plants of threelines derived from plants grown from seed of the seed deposit that wereselfed, were used. These lines are AG2971, AG2973, and AG3086.

Each plant was scored for the amount of thrips infestation, based on thescale explained in Table 2. Symptoms were scored when the cabbage headswere mature. The skilled person is not bound to using this scale but canalso use a scale with another subdivision of categories as long as thescoring will be done at the same stage, i.e. when the cabbage head ismature. This is not of influence on the final result of the screening.

TABLE 2 Scoring of thrips infestation. Score Symptoms 1 No symptoms/nodamage High resistance 2 Occasional small symptoms on outer leaves 3Minor damage. Max. 20% of head's surface Intermediate is covered bysymptoms, only outer leaves resistance are infected. 4 Medium damage.Max. 50% of the head's surface (all leaves accumulated) is covered bysymptoms. The symptoms are max. in the second and third layer. 5 Heavydamage. More than 50% of the head's Susceptible surface (all leavesaccumulated) is covered by symptoms. Damage also observed in deeper leaflayers

In Table 3 the scores of the trial are summarized. It is clear that allplants of the invention display a significantly higher resistanceagainst thrips.

In field trials with a high disease pressure, even highly resistantplants show occasional symptoms of thrips infection. This can e.g. bethe case when attractant plant species are used. In order to make a faircomparison between different trials using natural infection the samecomparison varieties should be used, because the relative differences indamage observed by thrips infestation will approximately be the samewhile the mean scores of same plants in different trials can deviatesubstantially.

TABLE 3 Score of thrips resistance field trial. Number of plants MeanMaterial screened score AG6359-35/39 17 1 Resistant (NCIMB 41760) AG297114 1.1 Resistant AG2973 16 1.2 Resistant AG3086 4 1.2 ResistantLangendijker 22 3.1 Intermediate Bewaar Tacoma 6 3 Intermediate Multima6 3 Intermediate Hurricane 10 4.4 Susceptible Rinda 10 5 Susceptible

Example 2

Transfer of Thrips Resistance to Susceptible Plants

A thrips resistant plants of the invention AG 2973-35 (see Table 2 forresistance scores), was crossed with a susceptible plant FM 2979-01.Plants of the F1 were observed in a field trial as described inExample 1. No highly thrips resistant plants were observed.

From the F1 population a plant was selected which was selfed to obtain apopulation of F2 plants. The F2 was placed in a field trial as describedin Example 1. Resistance scores are summarized in Table 4.

The segregation of the F2 population demonstrates that the inheritanceof the resistance of the invention is comparable with that of amonogenic additive trait (highly resistant : intermediate resistant:susceptible=1:2:1). Depending on the genetic background of thesusceptible parent plant there can be a different distribution betweenintermediately resistant and susceptible plants observed in the F2.

TABLE 4 Resistant Intermediately Susceptible F2 population plantsresistant plants plants Chi-square F2(AG 2973- 24 59 32 1.24 35 × FM2979- 01)

The invention is further described by the following numbered paragraphs:

1. A Brassica plant in particular a Brassica oleracea plant comprising agenetic determinant, which when homozygously present confers highresistance against Thrips tabaci, and which is as found in plants grownfrom seeds of which a representative sample is deposited with the NCIMBunder NCIMB accession number 41760.

2. A Brassica plant of paragraph 1, which is homozygous for the geneticdeterminant and resistant against Thrips tabaci.

3. The Brassica plant of paragraph 1 or paragraph 2, wherein the saidgenetic determinant in the seeds of NCIMB deposit 41760 is located onchromosome 2 and linked to marker BO00200 (SEQ ID NO: 1) and/or markerBO00277 (SEQ ID NO: 2) and/or marker BO00602 (SEQ ID NO: 5).

4. Seed comprising the genetic determinant as defined in any one of theparagraphs 1 to 3.

5. Seed of paragraph 4, wherein the plant that can be grown from theseed is resistant to Thrips tabaci.

6. Progeny of a Brassica plant of anyone of the paragraphs 1 to 3 orprogeny of plants grown from seeds of paragraph 4 or paragraph 5,wherein the plant comprises the genetic determinant as defined in anyone of the paragraphs 1-3.

7. Progeny plant of paragraph 6 wherein the progeny plant is resistantagainst Thrips tabaci.

8. Propagation material derived from a plant of any one of theparagraphs 1 to 3, wherein the propagation material comprises thegenetic determinant as defined in any one of the paragraph 1 to 3.

9. Propagation material capable of growing into a plant as claimed inany one of the paragraphs 1 to 3.

10. Propagation material of paragraph 8 or paragraph 9, wherein thepropagation material is selected from the group consisting ofmicrospores, pollen, ovaries, ovules, embryos, embryo sacs, egg cells,cuttings, roots, root tips, hypocotyls, cotyledons, stems, leaves,flowers, anthers, seeds, meristematic cells, protoplasts, and cells.

11. Tissue culture of propagation material of any one of the paragraphs8 to 10.

12. Harvested part of a Brassica plant of any one of the paragraphs 1-3,6 or 7, which harvested part is in particular selected from the groupconsisting of cabbage head, curd, stem, leaf, sprout, root and seed,optionally in processed form.

13. Harvested part of paragraph 12, wherein the harvested part is a foodproduct.

14. A nucleic acid molecule causative of resistance against Thripstabaci, comprising a DNA sequence, which is linked to marker BO00200(SEQ ID NO: 1) and/or marker BO00277 (SEQ ID NO: 2) and/or BO00602 (SEQID NO: 5) located on chromosome 2, in particular located on chromosome 2between marker BO00458 (SEQ ID NO: 7) and marker BO01225 (SEQ ID NO: 6),or a resistance conferring part of said nucleic acid molecule.

15. Use of the markers as defined in paragraph 3, and/or use of thenucleic acid molecule of paragraph 14, to identify or develop Thripstabaci resistant plants, or develop other markers linked to the geneticdeterminant as defined in anyone of the paragraphs 1 to 3.

16. Use of the markers of paragraph 2, or use of the nucleic acidmolecule of paragraph 13, to develop other markers linked to the geneticdeterminant as defined in paragraph 2.

Having thus described in detail preferred embodiments of the presentinvention, it is to be understood that the invention defined by theabove paragraphs is not to be limited to particular details set forth inthe above description as many apparent variations thereof are possiblewithout departing from the spirit or scope of the present invention.

What is claimed is:
 1. A method for identifying Thrips tabaci resistantplants comprising detecting marker BO00200 (SEQ ID NO: 1) and/or markerBO00277 (SEQ ID NO: 2) and/or marker BO00602 (SEQ ID NO: 5) in the DNAof said plant, which markers are linked to a nucleic acid moleculecausative of resistance against Thrips tabaci as found in plants grownfrom seeds from which a representative sample is deposited with theNCIMB under NCIMB accession number 41760 and is located on chromosome 2.2. A method for selecting Thrips tabaci resistant plants, comprising thesteps of detecting the presence of marker BO00200 (SEQ ID NO: 1) and/ormarker BO00277 (SEQ ID NO: 2) and/or marker BO00602 (SEQ ID NO: 5) inthe DNA of said plant, which markers are linked to the nucleic acidmolecule causative of resistance against Thrips tabaci as found inplants grown from seeds of which a representative sample is depositedwith the NCIMB under NCIMB accession number 41760 and is located onchromosome 2, thereby identifying Thrips tabaci resistant plants, andselecting the identified plants as plants being resistant against Thripstabaci.
 3. The method of claim 1, wherein the nucleic acid moleculecausative of resistance against Thrips tabaci is located on chromosome 2between marker BO00458 (SEQ ID NO: 7) and marker BO01225 (SEQ ID NO: 6).4. The method of claim 2, wherein the nucleic acid molecule causative ofresistance against Thrips tabaci is located on chromosome 2 betweenmarker BO00458 (SEQ ID NO: 7) and marker BO01225 (SEQ ID NO: 6).